This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Primary Objectives To describe the pharmacokinetic (PK) parameters during pregnancy of selected antiretroviral (ARV) drugs currently used in the clinical care of pregnant HIV infected women, and to determine if standard therapeutic dosing regimens of these antiretroviral drugs produce adequate drug exposure during pregnancy compared to a) historical data from non-pregnant adults and b) the same women in the study cohorts during the post partum period. Secondary Objectives To compare antiretroviral drug concentrations in plasma from cord blood with those in maternal plasma at the time of delivery. To indirectly assess the induction of cytochrome P450 3A4 by determining the ratio in urine of 6 beta hydroxycortisol to cortisol. To determine plasma protein binding of atazanavir, fosamprenavir, lopinavir, nelfinavir and tipranavir during pregnancy and postpartum.